Help! I’m a Prisoner in the Library! by Eth Clifford, 1979.
Harry Onetree is taking his two daughters, Mary Rose and Jo-Beth, to stay with their aunt on a snowy evening because their mother is about to have a baby and will soon be in the hospital. But, Harry has a habit of being careless and doing things at the last minute. In spite of practical Mary Rose’s warning that they’re running low on gas, Harry doesn’t stop to get any until they finally run out, and he has to hike through the snow back to the last gas station they passed.
Before their father gets back, Jo-Beth, the younger sister, declares that she has to go to the bathroom. Long-suffering Mary Rose finds one for her in a nearby library just before closing time. But, it’s not an ordinary library. It’s actually an old mansion which has been converted into a branch library for children. It has some fantastic displays, including an old wooden wagon called a “kid hack” which was once used to carry children to school, like a school bus. Unfortunately, the girls get distracted by this strange library. The girls forget about the library closing, and the librarian, not knowing that they’re there, locks them in for the night.
Meanwhile, the blizzard outside is getting worse, and their father has returned to the car and realized that they’re missing. The girls try to call the police, but they refuse to listen, thinking it’s a prank. Melodramatic Jo-Beth thinks that they’re doomed to starve to death in the library, trapped by the blizzard. Then, the girls hear a mysterious “thump” from upstairs. It turns out that they’re not alone in the library . . .
The Mary Rose and Jo-Beth books are fun with the way Jo-Beth delights in imagining doom and gloom while Mary Rose tries to work out a practical solution to their problems. The books in this series are also frequently about something other than the immediate mystery that the girls face. In this case, the girls learn about the history of the old house and how it became a branch library and how old buildings, even though they are beautiful and have a history to them, may face destruction if people don’t care enough about them or find a way to put them to some useful purpose.
This is the first book in the Mary Rose and Jo-Beth Mysteries.